The invention relates generally to a thrust control device for gas turbine jet engines and more specifically to combined jet gas divergence reversing and aircraft vectoring when used in conjunction with a variable convergent nozzle.
A common method for the diverging engine jet is by translating the engine center body or plug. This method requires the placement of actuation means within the engine exhaust stream. This positional placement subjects the actuation means to extreme heat, which requires that the structure and actuation mechanism be extremely heavy, thereby lowering the overall efficiency of the aircraft.
Another method for divergence of engine exhaust gases is by translating the outer wall or cowling structure surrounding the engine exit nozzle. This method is limited in its cross-sectional nozzle variation capabilities due to the predetermined optimum inner nozzle surface configuration and the slope or incline of its translation track.
These methods of divergence do not include thrust reversing capabilities; therefore, for combined operation, there must additionally be provided on the aircraft one of the many known thrust reversing mechanisms. The utilization of two separate systems results in an increase of aircraft structure weight and adds to the complexity of controlling the combined apparatus.
U.S. Pat. No. 3,779,010 teaches a combination thrust reverser with means for varying the effective nozzle throat area for thrust divergence. This teaching has several disadvantages; namely, there is only one position of cross-sectional nozzle variation and a portion of the gas stream is directed through the nozzle wall to the side of the aircraft, reducing the thrust efficiency of the engine.
These and various other methods for nozzle throat area variations and reversing are equally as complex as the above methods, are excessively heavy, and generally restrict engine accessibility for maintenance and repair due to the time and effort required to remove from and reinstall the various mechanisms on the aircraft.